Audion tube



May 19, 1931. G. A. YANOCHOWSKI AUDION TUBE Filed Jan. 29 1926 EFF? as.

Patented May 19, 1931 it fiJNII o[STATES PAT'E GEORGE A. Ynivocnowsxr,or LA GRANGE, ILLINOIS, Assreiroa TO KELLoGe-swITc H- AND SUPPLYCOMPANY, or CHICAGO, ILLIrIoIs, A. GOREOR-ATION. or

. BOARD ILLINOIS AUnIoN TUBE This invention relates to audion-tubes andparticularly to 'audion tubes of the type in which the cathode is heatedindirectly by being mounted in engagement with a heating element ofporcelain or other suitable material which may be heated by a resistancefilament therein.

It has been found that tubes of this charstantially centrallyofthe coilwhich, forms j w acter are rendered more difficult to evacuate by thefact that the porcelain or other material employed as a mounting for thecathode continues to discharge gas, even after being heated for aconsiderable period of time.

The object of the present invention is the provision of a tube havingmeans for preventing the gases discharged by the cathode heating elementfrom entering the evacuated portion of the tube. 7 One of the featuresof the invention is the tubular cathode having one end closed and theedge or rimof the other end sealed into the glass envelope of the tubewhereby the heating element positioned within the cathode is separatedvfrom. the interior of the tube.

Other features and advantages will appear from time to time as thedescription of the invention progresses.

It is believedthe further disclosure of the invention will be understoodmost readily from a detailed description thereof taken in connectionwith the accompanying drawings,

in which Fig. 1 is a longitudinal section through a tube constructed inaccordance with one embodiment of the invention, Fig. 2 is an enlargedview of a portion of the cathode and the split collar attached there to,and Fig. 3 is a section taken along the line 33 of Fig. 2. j

Referring now to the drawings, 10 indicates the usual stem of glass orlike material in which are sealed the conductor elements 11, 12 and 13.Conductor 11 carries at its upper end the plate 14 and at its lower'endthe terminal15. Conductor 12 carries the grid 16 and terminates at itslower end in the terminal 17. Conductor13 is joined at at its lower endto terminal 19. The plate 14 and grid 16 may be of theusualconstruction.

Inte ral with or joined to thestem. 10 is the bul or envelope 2() ofglass. Thebulb, at the upper end thereof, has the reduced portion 21 andis provided substantially .cen- 'trally' of the upper end-,withtheopening .22.

The cathode 18 projects downwardly subthe grid 16, and in thepresentmodification, may'in shape resemble a slender, miniature test tube.Asherein disclosed, it consists of a slender tube 18. closed at itslower end as indicated at 18. The upper end of the tube 18' is flaredoutwardly and sealed to the glass surroundingopening 22. This maybe donebefore the reduceduportion 21 is' connectedtothe' envelope 20. The tube18. and cathode portion 18 may be formed of thin sheet metal and theportion 18 may, if desired, be coated with oxides or other compoundstofassist in the emission of electrons.

I -The cathode acts to seal the evacuated in.-

terior of the tube/from the recesswithin the L cathode which isoccupiedby the heating element 24 of porcelain orother satisfactory re-,fractory material. If desired, the core 24 maybe tubular in form-andcement. maybe inserted in the. tube 18 at the oppositeends of core 24asindicated at 23. Within the porcelaincore 24 is the resistancefilament 25 by means of which the core 24 and, therefore, the cathode 18arehea-ted.

as V

a Fixed to the reduced portion 21 0f bulb 2O is a cap 26 of insulatingmaterial within which is'secured the laterally extending terminals 27.Conductors 28 passdownwardly 'aboveexplained, it has'beenfound that theporcelaincore of the cathode, such as above disclosed, whenheated willcontinue togive off more or'less gas for a considerable time;

thus renderingthe evacuating process long and expensive or resulting ina less perfect loo evacuation of the tube than is desirable. By thepresent invention the procelain core or refractory material within saidtubular cathode having parallel orifices extending thereheating elementis contained within the closed through, a heating element extendingthrough cathode tube and, therefore, the gases given off by said scoredo not pass into the tube, but instead pass upwardly through the cathodeelement. If desired, a small ventilating hole may be provided in the cap26 to permit the escape of the gas given off by the heater element.

' While but a single form of tube is shown in the present disclosure, itis to be understood that many modifications are contemplated and theinvention should be limited, therefore, only by the scope of theappended claims.

Having described my invention what I claim is new and desire to secureby Letters Patent of the United States is 1. An audion tube including anevacuated bulb having reduced end portions, av tubular cathode memberWithin said bulb the inner end of which is closed and its outer endflared and sealedtothe upper reduced end portion of said bulb wherebythe interior of the tubular cathode is separated from the evacuatedportion of the bulb, a refractory member within said cathode having apair of parallel orifices therein, a looped resistance element extendingthrough said orifices, a top cap fitted onto the upper reduced portionof said bulb, terminals for said cap connected to said heat ing element,a base member fitted onto the lower reduced portion of said bulb, aterminal supported by said base member, and a split collarcarried bysaid terminal making connection with said tubular cathode forpositioning the same and for extendingthe electrical connection to saidcathode.

2. An audion tube including an evacuated envelope having upper and lowerreduced end portions, a supporting press connected to the lower reducedend portion of said envelope, a grid and a plate supported by saidpress, a tubular cathode extending within said envelope having its oneend closed and its other end flared and sealed to the upper reducedportion of said envelope, a looped heating element enclosed inrefractory material extending within said tubular cathode, a top capfitted onto the reduced portion of said envelope and carrying terminalsconnected to said heating element, a support connected to said press andprovided with a collar attached to said tubular cathode, and a bottombase fitted onto the lower reduced end portion of said envelope andcarrying terminals connected to said grid, plate and cathode.

3. An audion tube includlng an evacuated envelope having reduced endportions, a

lower press for said tube connected to said envelope, a tubular cathodeenclosed in one end and having its other end sealed to the reduced upperend portion of said envelope,

said orifices, a grid and a plate supported by said press, a supportingmember held by said press and provided with a split collar encirclingsaid tubular cathode for holding the cathode in position relative tosaid grid and plate, a bottom base fitted onto the lower reduced portionof said envelope and supporting terminals connected to said grid, plateand cathode, and an upper cap fitted onto the upper reduced portion ofsaid envelope and carrying terminals connected to said heating element,such structure separating the refractory material and its heatingelement from the evacuated portion of the tube.

In testimony whereof I have signed this specification.

GEORGE A. YANOGHOWSKI.

